Diagnosis and official regulatory testing for bovine trichomoniasis in the state of Washington
Major highlights of bovine trichomoniasis testing
- Bovine trichomoniasis is a disease that causes reduced reproductive performance in cattle herds.
- Bovine trichomoniasis is a disease regulated by the Washington State Department of Agriculture (WSDA-State Veterinarian).
- Control of trichomoniasis in cattle herds requires culling of infected carrier bulls. The required sample for "official" detection of trichomoniasis in bulls is a preputial scraping taken by an accredited veterinarian registered by the WSDA as proficient in the procedure.
- Detection of infected carrier bulls requires laboratory testing.
- The official laboratory test in the state of Washington for bovine trichomoniasis is the individual or pooled polymerase chain reaction (PCR) test
- WSU-WADDL is an official testing laboratory for bovine trichomoniasis in the state of Washington.
- Samples for bovine trichomoniasis testing should be submitted to the laboratory on a "WADDL Trichomoniasis PCR Form" and submitted in Trichomonas transport medium.
- Trichomonas testing by pooled PCR (up to 5 bulls from the same owner) now allowed by WSDA and available at WSU-WADDL (see #8, #10 and #12 below)
- Two methods of sample collection and submission now allowed by WSDA and available at WSU-WADDL (see #8 below).
- New easier handling Trichomonas test media tube container now available from BioMed Diagnostics Inc. (see # 8 below)
1. What is trichomoniasis?
Bovine venereal trichomoniasis is caused by Tritrichomonas foetus, a flagellate protozoan parasite. T. foetus lives in the reproductive tracts of bulls and cows and has worldwide distribution.The widespread use of artificial insemination in many areas of the world has helped to reduce the prevalence. Trichomoniasis is still of importance in herds where artificial insemination is not used.
2. How is trichomoniasis transmitted?
Venereal transmission can occur from an infected bull to an uninfected cow (or heifer), or from an infected cow (or heifer) to an uninfected bull. Bulls are the main reservoir of the trichomoniasis, and bulls greater than 4 years of age tend to be long-term carriers. For this reason samples from bulls are preferred for diagnosing and controlling the disease in cattle herds.
3. What are the clinical signs of trichomoniasis in individual cattle?
Chronically infected bulls show no lesions or clinical disease. Infected bulls appear normal, breed normally, and can infect an entire herd through natural service. In the newly infected cow or heifer (in those never before infected with T. foetus), there is inflammation of the reproductive tract (vagina, cervix, uterus), which may result in a discharge from the vagina or, in severe cases, pyometra (uterus distended with pus and the cow’s inability to cycle). If the cow is pregnant, the infection results in placentitis (inflammation of the birth membranes) and causes early abortion (1-16 weeks of gestation).
4. How do I know if my cattle herd has trichomoniasis?
A tentative diagnosis of trichomoniasis as a cause of reproductive failure in a herd is based upon clinical history (presence of clinical signs in individual cows in a bull bred herd), signs of early abortion, repeated returns to service, high percentage of unbred cows, and irregular estrus cycles. Confirmation of trichomoniasis requires demonstration of T. foetus parasites by laboratory testing.
5. How do I get trichomoniasis out of my cattle herd or prevent trichomoniasis from entering my cattle herd?
Control of trichomoniasis in cattle herds requires identification of bulls infected with T. foetus by laboratory methods and removal of the infected bulls from the herd. Also, testing all purchased bulls for T. foetus before entering the herd will prevent introduction of trichomoniasis into your herd. Bulls become chronically infected with T. foetus, are long-term carriers and can serve as the source of trichomoniasis in cattle herds from one breeding season to the next. Cows with trichomoniasis spontaneously clear infection in 90-95 days and are not a source of T. foetus infection from one breeding season to the next. There is no effective method for treating T. foetus-infected bulls. Infected bulls are generally culled from the herd and sold for slaughter.
6. What samples do I take for laboratory identification of trichomoniasis?
In bulls, preputial smegma (preputial scraping) is the optimal sample. In cows and heifers, T. foetus parasites are most reliably identified from placental fluids, placenta, stomach contents of aborted fetuses, uterine washings, pyometra discharge, or vaginal mucus. Herd-based diagnosis is most reliably made from preputial scrapings of bulls or vaginal scrapings/fluids from cows.
7. How are samples collected for laboratory identification of trichomoniasis?
Appropriate sample collection for accurate diagnosis of trichomoniasis is critical. In infected bulls, T. foetus parasites live deep in the preputial folds (microscopic crevices inside the prepuce) requiring a preputial scraping below the mucosal surface of the prepuce in order to reach the embedded parasites. The scraping is generally accomplished with an artificial insemination pipette (dry pipette technique) or special soft metal brush. For official regulatory testing, sampling must be done by a veterinarian certified and registered with the Washington State Department of Agriculture (WSDA) for trichomoniaisis sample collection. An online course on Trichomoniasis Testing and a video of the collection technique in bulls is available at the web link below provided by the Washington State Department of Agriculture (WSDA) and WSU Veterinary Medicine Extension. http://vetextension.wsu.edu/bovine/trich/
8. How should I store samples for trichomoniasis testing prior to shipping and how should they be shipped?
Samples submitted to WSU-WADDL should be collected into Trichomonas test media. Trichomonas test media is manufactured by Biomed Diagnostics, Inc. and is available directly from the company (Phone: 800-964-6466). We prefer use of the TF transit tube (catalogue # 60-1010 for a 10-pack or catalogue # 60-1050 for a 50-pack). The TF transit tubes are also available from MWI Veterinary Supply (Phone: 800-824-3703), Fisher Scientific (Phone: 800-766-7000), and other vendors. "In Pouch" TF media is still acceptable, but costs about $1.00 more for each (catalogue # 11-1001 (20 pouches) or 11-1002 (100 pouches).
For a valid Official test follow one of the following submission procedures; Method 1: Ship the samples by overnight courier so that they arrive at the lab within 48 hours of collection. For this method ship samples at room temperature (no ice pack)
Method 2: Incubate the samples at 37 degrees centigrade for 24 hours, then freeze the sample. For this method, ship with an ice pack at your convenience using an overnight courier.
Samples should be submitted on the WADDL Trichomoniasis PCR Accession Form. Please fill out the form completely and check either individual PCR or Pooled PCR as appropriate (see criteria for Pooled PCR testing below in #12).
9. Is specialized training required for collection of samples for laboratory identification of trichomoniasis?
Yes. The Washington State Department of Agriculture (WSDA) and State Veterinarian require that veterinarians receive special training, certification and registration for collection of preputial samples from bulls. Only veterinarians registered with the WSDA can collect samples for official trichomoniasis testing in bulls. The WSDA Animal Services Division provides educational seminars to veterinarians on proper trichomoniasis sampling and handling techniques. An online course on Trichomoniasis Testing and a video of the collection technique in bulls is available at the web link below provided by the Washington State Department of Agriculture (WSDA) and WSU Veterinary Medicine Extension. http://vetextension.wsu.edu/bovine/trich/ WSDA will recognize other states' official trichomoniasis collection protocols when veterinarians outside Washington State collect the samples.
10. What are the laboratory tests for trichomoniasis?
Official regulatory tests for trichomoniasis vary state to state but generally are restricted to culture or polymerase chain reaction (PCR) methods. PCR is accepted as the official test for trichomoniasis by the Washington State Department of Agriculture (WSDA). WSU-WADDL is the only Washington laboratory recognized by the State Veterinarian for official trichomoniasis testing and conducts testing using individual quantitative PCR (qPCR) or pooled quantitative PCR. For pooled PCR testing submit individual preputial scraping samples in TF media (as described in #8 above) and samples will be pooled in the laboratory (DO NOT POOL SAMPLES IN THE FIELD PRIOR TO SUBMISSION). Any positive pooled PCR samples require followup testing of individual samples within the positive pool in order to identify the positive individual bull(s).
The current cost of Trichomonas testing by PCR is listed in the current WADDL website fee schedule under the “Molecular Diagnostics” section.
11. What are the Washington State Department of Agriculture (WSDA) regulations regarding trichomoniasis?
Because bulls with trichomoniasis do not show clinical signs of infection and because trichomoniasis can cause economic losses to Washington cattle herds through significant reproductive failure, the WSDA and State Veterinarian require all breeding bulls entering the state of Washington be shown free of trichomoniasis. The bovine trichomoniasis requirements are published in Washington Administrative Code (WAC) document #16-54-086, “Bovine Trichomoniasis Requirements”. The latest version of the requirement should be consulted and is available on the WSDA website at http://apps.leg.wa.gov/wac/default.aspx?cite=16-54-086
Some brief highlights of the WAC Bovine Trichomoniasis Requirements are listed below.
Breeding bulls may be imported into state of Washington if:
If the bulls originate from a herd where one or more bulls or cows have been found infected with bovine trichomoniasis within the past twelve months or have unknown status, the bulls must have two negative qPCR tests one week apart. The samples for each test must be collected within thirty days before cattle are imported into Washington state, and an import permit must be obtained from the director and include a certifying statement that the bulls originated from an infected herd.
Virgin bulls are exempt from bovine trichomoniasis test requirements. If sold, virgin bulls must be officially identified and accompanied by a certificate signed by the owner or the owner's designee that they have had no breeding contact with female cattle.
Registered veterinarians shall only utilize official laboratories recognized by the state veterinarian for testing of trichomoniasis samples.
Polymerase chain reaction is accepted as an official test when completed by a qualified laboratory approved by the director and when shipped and received by laboratory by the two methods described in #8 above.
12. What are the WSDA requirements for pooled PCR testing?
WSDA has had Trichomoniasis regulations since 2008. Testing protocol advancements since the implementation of the regulations has allowed WSDA to revisit the issue of pooling with low risk situations or for non-regulatory purposes. This action still complies with the Trichomoniasis import regulations for import in WAC 16-54-086.
The criteria where pooling of up to 5 bulls will be allowed are:
Bulls that are over 18 months old cannot be exempted as virgin bulls, and have had no breeding contact with females.
Bulls sampled for a herd diagnostic test without regulatory implications.
As part of a disease investigation, pooling may be allowed if the herd does not have a history of infection or in the judgment of the herd veterinarian Trichomoniasis infection is unlikely.
Pooling will NOT be allowed for:
Multiple owners for a single pool. This effectively eliminates pooling as an option at livestock markets.
Infected herds or herds with a history of infection within the past 12 months.
SOME STATES WILL NOT ACCEPT POOLED SAMPLES FOR IMPORTATION TESTING INTO THEIR STATE. CHECK THE STATE OF DESTINATION REQUIREMENTS BEFORE REQUESTING POOLED SAMPLES.